Interesting. My 18 yo niece put Metallica on her (long) list of bands she likes. I didn't recognize the names of any of the other dozen or so she talked about. I didn't like Metallica when I was young, but they have grown on me over the years...they definitely played _music_ that was powerful. I realize that now. Same with Rush and Beatles. So many great bands from the golden era.
As far as the given list of just three, its a toss up between Def Leppard and Van Halen. I will have to go with Def Leppard...their music progressed over time. Van Halen just became more of the same (earlier albums were better, more raw).
Incidentally, have you seen the 1969 video recording of Led Zeppelin's 'Babe, I'm gonna leave you'? I just came across it:
listen to that one, then listen to the polished studio version. wow. real music being made.